Heat exchanger core constituted by folded plates



Feb. 23, 1954 E A. LUNDSTROM HEAT EXCHANGER CORE CONSTITUTED BY FOLDED PLATES Filed May 22, 1951 PERFORA TED STRIP FIN INVENTOR.

70267 4- lands/ m.

BY q e u ATTORNE):

Patented Feb. 23, 1954 I HEAT EXCHANGER CORE CONSTITUTED BY FOLDED PLATES Ernest A. Lundstrom, Valley Stream, N.

Air Pr signor to The York, N. Y.

Y., as-

eheater Corporation, New

Application May 22, 1951, Serial No. 227,580 Claims. (Cl. 257-245 The present invention relates to plate type exchangers utilized for the transmission of heat between two confined fluids and particularly to an improved heat exchanger core having wall members bounding the fluid passages provided with extended surface in the form of fins.

A well known type of apparatus for the transfer of heat between two confined fluids, such as hot gases and relatively cool air, is made up of a plurality of spaced metallic plates forming passages through alternate ones of which the hot gas flows in heat exchange relationship with the air that traverses the intermediate passages. The spaces between the parallel plates are closed along one pair of opposite edges to bound the sides of the passage for the air to be heated and heating gas passage is likewise closed along one pair of opposite side edges, which sides may be those extending parallel to the closed edges of the air passage in case of parallel flow, or along the adjacent sides in case of transverse flow. Such spaced plates form a core that is usually enclosed within a housing with which are associated the inlet and outlet manifolds and the supply and discharge ducts for the two fluids.

To increase the heat transfer efiiciency heat exchangers of this type frequently have the walls of the fluid passages provided with extended surface in the form of fins extending into the path of the fluids and serving to increase the conduction of heat to and through the walls bounding the passages. In the application of Sven Holm Serial No. 752,008 dated June 3, 1947, now Patent No. 2,595,457 granted May 6, 1952, there is disclosed a heat exchanger core having extended surface on the passage walls comprising sinuously bent wires forming loops extending between the walls bonding the gas passage and constituting pin-like fins extending from these walls. On the opposite face of these walls extended surface is provided in the form of channel members extending in the air stream parallel to the direction of fluid.

The present invention is directed in an improved heat exchanger core having pin-fins of this nature in the gas passages and rib or strip fins in the air passages, these fins according to the invention being integral with the passage walls separating the fluids and created by forming parallel rows of apertures in flat plates and then specially folding the plates so as to raise portions including the perforations from the original plane of the plate proper.

The invention will best be understood upon consideration of the following detailed description of illustrative embodiments thereof when read in conjunction with the accompanying drawings in which:

Figure l is an end view of part of a heat exchanger matrix or core in which the plate members that form walls between fluid passages are specially formed to provide extended surface in the form of pin-fins for the gas passages and interrupted longitudinal strip fins in the air passages;

Figure 2 is a longitudinal sectional view through the heat exchanger passages along the line 22 in Figure 1;

Figure 3 is a perspective view of part of a plate from which the passage walls areformed showing the special manner of perforating it to provide for the formation of the extended fin surface; and

Figure 4 is a perspective view of part of one of the matrix components formed when the plate of Figure 3 has been folded to constitute a passage wall with fins projecting from both surfaces into the air and gas passages separated by the wall.

In the manufacture of the heat exchanger a metallic plate of a length sufficient to provide in the finished exchanger a transverse wall of the desired width is formed with pairs of rows l2 and M of perforations l6 of equal size which rows lie between other pairs of rows 18 of larger perforations 20, here shown as twice the length of the perforations IS. The perforated plate ID with multiple series of perforations is then folded along lines paralleling, or coinciding with, the axes of the rows of perforations so that the ligaments I! and I9 lying between the perforations in rows l2 and I4 and also the ligaments lying between the perforations 20 in the rows I8 become parts of the fins projecting from the wall dividing the fluid passage, these walls being formed by the imperforate portions 22 of the plate I0 that are located between the rows of larger and smaller perforations. The plate It] is folded downwardly, for example, along the line A-A that bisects the perforations 20 in the row I 8 and. the half portions 23 and 25 of the ligaments 2| are brought into contact so that a row of pin-like fins is formed extending transversely of the plate. At one side of the row of pin-fins the plate is bent upwardly along the line BB so that the pin-fins extend upright from the portions 22 of the plate that constitutes the passage wall. No fold is formed between the row l8 of large perforations 20 and the immediately adjacent row M of small perforations l6,

the next fold being in an upward direction along the line G-C intermediate the rows 12 and 14 of small perforations so that the ligaments l1 and I9 between the perforations in these rows are brought into contact. Thus, a perforated or a strip fin 30 is formed transversely of the plate. Following this the plate is folded downwardly on the line D-D to form the imperforate portion [9 in alinement with the wall part 22. Subsequently by folding the plate downwardly along the line A--A bisecting the next row [8 by large perforations 22 a second row of pin-fins 2B is formed projecting in upright relation across the plates. Then by folding the plate upwardly along the second line B-B a further part 22a of the wall is formed in alinement with the part 32. Repetition of the folding procedure described above results in producing a plurality of rows of pin-fins on one side of the plate and interrupted strip fins on the opposite side of the plate. These fins are made up of a plurality of folds in one direction extending normal to the plane of the plate each contiguous with a fold in the opposite direction with still another fold in the first mentioned direction intervening between and folded in the same direction as these folds so that single folds extending in one direction lie intermediate double folds that extend in both directions from the plane of the plate.

The heat exchange core is made up of a plurality of fin wall components formed by folding plate members as described above and assembled by superimposing a number of these plates upon each other with the fins in the adjacent components offset so that the double folds of one component aline and rest upon with the single folds of the adjacent components as shown in Figure 1 thus creating a honeycomb heat exchanger core with passages for the heating gas intervening between alternate passages for the air or other fluid to be heated. The sides of the passages of the heat exchanger core are closed by the plates 40 as indicated in Figure 1 and the extreme passages at the top and bottom of the core are closed by plates 32.

What I claim is:

1. In a heat exchanger core having the walls that separate passages for the flow of fluids between which heat is exchanged constituted by plate members each formed with a plurality of folds in one direction normal to the plane of the plate and each contiguous with a fold in the opposite direction to constitute double folds with another fold in said one direction intervening between and folded in the same direction as said first folds to provide single folds extending in 1 said one direction lying intermediate double folds that extend in both directions from the plane of a plate, pairs of said plates being superimposed in relatively reversed relation so that each single fold in one plate that extends in a single direction alines with a pair of folds that extends in both directions from the other plate, and vice versa.

2. A heat exchanger core having the walls that separate passages for the flow of fluids between which heat is eXchanged constituted by plate members each formed with a plurality of folds in one direction normal to the plane of the plate and each contiguous with a fold in the opposite direction to constitute double folds with another fold in said one direction intervening between and folded in the same direction as said first folds to provide single folds extending in said one direction lying intermediate double folds that extend in both directions from th plane of a plate, pairs of said plates being superimposed in relatively reversed relation so that each single fold in one plate that extends in a single direction aiines with a pair of folds that extends in both directions from the other plate and vice versa; the distalends of the folds of one plate contacting the other plate to form passages of a width corresponding to the height of said folds.

3. A plate wall member as recited in claim 1 wherein the folds on one side of the sheet are cut away from their distal ends to locations adjacent the plane of the plate so that the remainin fold ligaments constitute pin-fins on said wall.

4. A plate wall member as recited in claim 3 wherein the folds that extend from the other side of each plate are perforated so that the ligaments between the adjacent perforations constitute pin-fins bridged at their distal ends by transverse ligaments.

5. A heat exchanger core having the walls separating passages for the flow of two fluids in heat exchange relation constituted by plate members each formed with a plurality of upward folds normal to the plane of the plate located contiguous with downward folds to constitute double folds with another upward fold intervening between said first fold to provide upward folds 1ying intermediate double folds that extend both upwardly and downwardly from the plane of a plate, pairs of said plates being superimposed in relatively reversed relation so that the single upward folds of one plate extend either upwardly or downwardly in'alinement with a double fold that extends both upwardly and downwardly from the other plate sheet and vice versa.

ERNEST A. LUNDSTROM.

References Cited in the file of this patent 

